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1/*
2 * arch/xtensa/kernel/process.c
3 *
4 * Xtensa Processor version.
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * Copyright (C) 2001 - 2005 Tensilica Inc.
11 *
12 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
13 * Chris Zankel <chris@zankel.net>
14 * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
15 * Kevin Chea
16 */
17
18#include <linux/errno.h>
19#include <linux/sched.h>
20#include <linux/sched/debug.h>
21#include <linux/sched/task.h>
22#include <linux/sched/task_stack.h>
23#include <linux/kernel.h>
24#include <linux/mm.h>
25#include <linux/smp.h>
26#include <linux/stddef.h>
27#include <linux/unistd.h>
28#include <linux/ptrace.h>
29#include <linux/elf.h>
30#include <linux/hw_breakpoint.h>
31#include <linux/init.h>
32#include <linux/prctl.h>
33#include <linux/init_task.h>
34#include <linux/module.h>
35#include <linux/mqueue.h>
36#include <linux/fs.h>
37#include <linux/slab.h>
38#include <linux/rcupdate.h>
39
40#include <asm/pgtable.h>
41#include <linux/uaccess.h>
42#include <asm/io.h>
43#include <asm/processor.h>
44#include <asm/platform.h>
45#include <asm/mmu.h>
46#include <asm/irq.h>
47#include <linux/atomic.h>
48#include <asm/asm-offsets.h>
49#include <asm/regs.h>
50#include <asm/hw_breakpoint.h>
51
52extern void ret_from_fork(void);
53extern void ret_from_kernel_thread(void);
54
55struct task_struct *current_set[NR_CPUS] = {&init_task, };
56
57void (*pm_power_off)(void) = NULL;
58EXPORT_SYMBOL(pm_power_off);
59
60
61#ifdef CONFIG_CC_STACKPROTECTOR
62#include <linux/stackprotector.h>
63unsigned long __stack_chk_guard __read_mostly;
64EXPORT_SYMBOL(__stack_chk_guard);
65#endif
66
67#if XTENSA_HAVE_COPROCESSORS
68
69void coprocessor_release_all(struct thread_info *ti)
70{
71 unsigned long cpenable;
72 int i;
73
74 /* Make sure we don't switch tasks during this operation. */
75
76 preempt_disable();
77
78 /* Walk through all cp owners and release it for the requested one. */
79
80 cpenable = ti->cpenable;
81
82 for (i = 0; i < XCHAL_CP_MAX; i++) {
83 if (coprocessor_owner[i] == ti) {
84 coprocessor_owner[i] = 0;
85 cpenable &= ~(1 << i);
86 }
87 }
88
89 ti->cpenable = cpenable;
90 coprocessor_clear_cpenable();
91
92 preempt_enable();
93}
94
95void coprocessor_flush_all(struct thread_info *ti)
96{
97 unsigned long cpenable;
98 int i;
99
100 preempt_disable();
101
102 cpenable = ti->cpenable;
103
104 for (i = 0; i < XCHAL_CP_MAX; i++) {
105 if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
106 coprocessor_flush(ti, i);
107 cpenable >>= 1;
108 }
109
110 preempt_enable();
111}
112
113#endif
114
115
116/*
117 * Powermanagement idle function, if any is provided by the platform.
118 */
119void arch_cpu_idle(void)
120{
121 platform_idle();
122}
123
124/*
125 * This is called when the thread calls exit().
126 */
127void exit_thread(struct task_struct *tsk)
128{
129#if XTENSA_HAVE_COPROCESSORS
130 coprocessor_release_all(task_thread_info(tsk));
131#endif
132}
133
134/*
135 * Flush thread state. This is called when a thread does an execve()
136 * Note that we flush coprocessor registers for the case execve fails.
137 */
138void flush_thread(void)
139{
140#if XTENSA_HAVE_COPROCESSORS
141 struct thread_info *ti = current_thread_info();
142 coprocessor_flush_all(ti);
143 coprocessor_release_all(ti);
144#endif
145 flush_ptrace_hw_breakpoint(current);
146}
147
148/*
149 * this gets called so that we can store coprocessor state into memory and
150 * copy the current task into the new thread.
151 */
152int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
153{
154#if XTENSA_HAVE_COPROCESSORS
155 coprocessor_flush_all(task_thread_info(src));
156#endif
157 *dst = *src;
158 return 0;
159}
160
161/*
162 * Copy thread.
163 *
164 * There are two modes in which this function is called:
165 * 1) Userspace thread creation,
166 * regs != NULL, usp_thread_fn is userspace stack pointer.
167 * It is expected to copy parent regs (in case CLONE_VM is not set
168 * in the clone_flags) and set up passed usp in the childregs.
169 * 2) Kernel thread creation,
170 * regs == NULL, usp_thread_fn is the function to run in the new thread
171 * and thread_fn_arg is its parameter.
172 * childregs are not used for the kernel threads.
173 *
174 * The stack layout for the new thread looks like this:
175 *
176 * +------------------------+
177 * | childregs |
178 * +------------------------+ <- thread.sp = sp in dummy-frame
179 * | dummy-frame | (saved in dummy-frame spill-area)
180 * +------------------------+
181 *
182 * We create a dummy frame to return to either ret_from_fork or
183 * ret_from_kernel_thread:
184 * a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
185 * sp points to itself (thread.sp)
186 * a2, a3 are unused for userspace threads,
187 * a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
188 *
189 * Note: This is a pristine frame, so we don't need any spill region on top of
190 * childregs.
191 *
192 * The fun part: if we're keeping the same VM (i.e. cloning a thread,
193 * not an entire process), we're normally given a new usp, and we CANNOT share
194 * any live address register windows. If we just copy those live frames over,
195 * the two threads (parent and child) will overflow the same frames onto the
196 * parent stack at different times, likely corrupting the parent stack (esp.
197 * if the parent returns from functions that called clone() and calls new
198 * ones, before the child overflows its now old copies of its parent windows).
199 * One solution is to spill windows to the parent stack, but that's fairly
200 * involved. Much simpler to just not copy those live frames across.
201 */
202
203int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
204 unsigned long thread_fn_arg, struct task_struct *p)
205{
206 struct pt_regs *childregs = task_pt_regs(p);
207
208#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
209 struct thread_info *ti;
210#endif
211
212 /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
213 SPILL_SLOT(childregs, 1) = (unsigned long)childregs;
214 SPILL_SLOT(childregs, 0) = 0;
215
216 p->thread.sp = (unsigned long)childregs;
217
218 if (!(p->flags & PF_KTHREAD)) {
219 struct pt_regs *regs = current_pt_regs();
220 unsigned long usp = usp_thread_fn ?
221 usp_thread_fn : regs->areg[1];
222
223 p->thread.ra = MAKE_RA_FOR_CALL(
224 (unsigned long)ret_from_fork, 0x1);
225
226 /* This does not copy all the regs.
227 * In a bout of brilliance or madness,
228 * ARs beyond a0-a15 exist past the end of the struct.
229 */
230 *childregs = *regs;
231 childregs->areg[1] = usp;
232 childregs->areg[2] = 0;
233
234 /* When sharing memory with the parent thread, the child
235 usually starts on a pristine stack, so we have to reset
236 windowbase, windowstart and wmask.
237 (Note that such a new thread is required to always create
238 an initial call4 frame)
239 The exception is vfork, where the new thread continues to
240 run on the parent's stack until it calls execve. This could
241 be a call8 or call12, which requires a legal stack frame
242 of the previous caller for the overflow handlers to work.
243 (Note that it's always legal to overflow live registers).
244 In this case, ensure to spill at least the stack pointer
245 of that frame. */
246
247 if (clone_flags & CLONE_VM) {
248 /* check that caller window is live and same stack */
249 int len = childregs->wmask & ~0xf;
250 if (regs->areg[1] == usp && len != 0) {
251 int callinc = (regs->areg[0] >> 30) & 3;
252 int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
253 put_user(regs->areg[caller_ars+1],
254 (unsigned __user*)(usp - 12));
255 }
256 childregs->wmask = 1;
257 childregs->windowstart = 1;
258 childregs->windowbase = 0;
259 } else {
260 int len = childregs->wmask & ~0xf;
261 memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
262 ®s->areg[XCHAL_NUM_AREGS - len/4], len);
263 }
264
265 /* The thread pointer is passed in the '4th argument' (= a5) */
266 if (clone_flags & CLONE_SETTLS)
267 childregs->threadptr = childregs->areg[5];
268 } else {
269 p->thread.ra = MAKE_RA_FOR_CALL(
270 (unsigned long)ret_from_kernel_thread, 1);
271
272 /* pass parameters to ret_from_kernel_thread:
273 * a2 = thread_fn, a3 = thread_fn arg
274 */
275 SPILL_SLOT(childregs, 3) = thread_fn_arg;
276 SPILL_SLOT(childregs, 2) = usp_thread_fn;
277
278 /* Childregs are only used when we're going to userspace
279 * in which case start_thread will set them up.
280 */
281 }
282
283#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
284 ti = task_thread_info(p);
285 ti->cpenable = 0;
286#endif
287
288 clear_ptrace_hw_breakpoint(p);
289
290 return 0;
291}
292
293
294/*
295 * These bracket the sleeping functions..
296 */
297
298unsigned long get_wchan(struct task_struct *p)
299{
300 unsigned long sp, pc;
301 unsigned long stack_page = (unsigned long) task_stack_page(p);
302 int count = 0;
303
304 if (!p || p == current || p->state == TASK_RUNNING)
305 return 0;
306
307 sp = p->thread.sp;
308 pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
309
310 do {
311 if (sp < stack_page + sizeof(struct task_struct) ||
312 sp >= (stack_page + THREAD_SIZE) ||
313 pc == 0)
314 return 0;
315 if (!in_sched_functions(pc))
316 return pc;
317
318 /* Stack layout: sp-4: ra, sp-3: sp' */
319
320 pc = MAKE_PC_FROM_RA(*(unsigned long*)sp - 4, sp);
321 sp = *(unsigned long *)sp - 3;
322 } while (count++ < 16);
323 return 0;
324}
325
326/*
327 * xtensa_gregset_t and 'struct pt_regs' are vastly different formats
328 * of processor registers. Besides different ordering,
329 * xtensa_gregset_t contains non-live register information that
330 * 'struct pt_regs' does not. Exception handling (primarily) uses
331 * 'struct pt_regs'. Core files and ptrace use xtensa_gregset_t.
332 *
333 */
334
335void xtensa_elf_core_copy_regs (xtensa_gregset_t *elfregs, struct pt_regs *regs)
336{
337 unsigned long wb, ws, wm;
338 int live, last;
339
340 wb = regs->windowbase;
341 ws = regs->windowstart;
342 wm = regs->wmask;
343 ws = ((ws >> wb) | (ws << (WSBITS - wb))) & ((1 << WSBITS) - 1);
344
345 /* Don't leak any random bits. */
346
347 memset(elfregs, 0, sizeof(*elfregs));
348
349 /* Note: PS.EXCM is not set while user task is running; its
350 * being set in regs->ps is for exception handling convenience.
351 */
352
353 elfregs->pc = regs->pc;
354 elfregs->ps = (regs->ps & ~(1 << PS_EXCM_BIT));
355 elfregs->lbeg = regs->lbeg;
356 elfregs->lend = regs->lend;
357 elfregs->lcount = regs->lcount;
358 elfregs->sar = regs->sar;
359 elfregs->windowstart = ws;
360
361 live = (wm & 2) ? 4 : (wm & 4) ? 8 : (wm & 8) ? 12 : 16;
362 last = XCHAL_NUM_AREGS - (wm >> 4) * 4;
363 memcpy(elfregs->a, regs->areg, live * 4);
364 memcpy(elfregs->a + last, regs->areg + last, (wm >> 4) * 16);
365}
366
367int dump_fpu(void)
368{
369 return 0;
370}
1/*
2 * arch/xtensa/kernel/process.c
3 *
4 * Xtensa Processor version.
5 *
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
8 * for more details.
9 *
10 * Copyright (C) 2001 - 2005 Tensilica Inc.
11 *
12 * Joe Taylor <joe@tensilica.com, joetylr@yahoo.com>
13 * Chris Zankel <chris@zankel.net>
14 * Marc Gauthier <marc@tensilica.com, marc@alumni.uwaterloo.ca>
15 * Kevin Chea
16 */
17
18#include <linux/errno.h>
19#include <linux/sched.h>
20#include <linux/sched/debug.h>
21#include <linux/sched/task.h>
22#include <linux/sched/task_stack.h>
23#include <linux/kernel.h>
24#include <linux/mm.h>
25#include <linux/smp.h>
26#include <linux/stddef.h>
27#include <linux/unistd.h>
28#include <linux/ptrace.h>
29#include <linux/elf.h>
30#include <linux/hw_breakpoint.h>
31#include <linux/init.h>
32#include <linux/prctl.h>
33#include <linux/init_task.h>
34#include <linux/module.h>
35#include <linux/mqueue.h>
36#include <linux/fs.h>
37#include <linux/slab.h>
38#include <linux/rcupdate.h>
39
40#include <linux/uaccess.h>
41#include <asm/io.h>
42#include <asm/processor.h>
43#include <asm/platform.h>
44#include <asm/mmu.h>
45#include <asm/irq.h>
46#include <linux/atomic.h>
47#include <asm/asm-offsets.h>
48#include <asm/regs.h>
49#include <asm/hw_breakpoint.h>
50
51extern void ret_from_fork(void);
52extern void ret_from_kernel_thread(void);
53
54void (*pm_power_off)(void) = NULL;
55EXPORT_SYMBOL(pm_power_off);
56
57
58#ifdef CONFIG_STACKPROTECTOR
59#include <linux/stackprotector.h>
60unsigned long __stack_chk_guard __read_mostly;
61EXPORT_SYMBOL(__stack_chk_guard);
62#endif
63
64#if XTENSA_HAVE_COPROCESSORS
65
66void coprocessor_release_all(struct thread_info *ti)
67{
68 unsigned long cpenable;
69 int i;
70
71 /* Make sure we don't switch tasks during this operation. */
72
73 preempt_disable();
74
75 /* Walk through all cp owners and release it for the requested one. */
76
77 cpenable = ti->cpenable;
78
79 for (i = 0; i < XCHAL_CP_MAX; i++) {
80 if (coprocessor_owner[i] == ti) {
81 coprocessor_owner[i] = 0;
82 cpenable &= ~(1 << i);
83 }
84 }
85
86 ti->cpenable = cpenable;
87 if (ti == current_thread_info())
88 xtensa_set_sr(0, cpenable);
89
90 preempt_enable();
91}
92
93void coprocessor_flush_all(struct thread_info *ti)
94{
95 unsigned long cpenable, old_cpenable;
96 int i;
97
98 preempt_disable();
99
100 old_cpenable = xtensa_get_sr(cpenable);
101 cpenable = ti->cpenable;
102 xtensa_set_sr(cpenable, cpenable);
103
104 for (i = 0; i < XCHAL_CP_MAX; i++) {
105 if ((cpenable & 1) != 0 && coprocessor_owner[i] == ti)
106 coprocessor_flush(ti, i);
107 cpenable >>= 1;
108 }
109 xtensa_set_sr(old_cpenable, cpenable);
110
111 preempt_enable();
112}
113
114#endif
115
116
117/*
118 * Powermanagement idle function, if any is provided by the platform.
119 */
120void arch_cpu_idle(void)
121{
122 platform_idle();
123}
124
125/*
126 * This is called when the thread calls exit().
127 */
128void exit_thread(struct task_struct *tsk)
129{
130#if XTENSA_HAVE_COPROCESSORS
131 coprocessor_release_all(task_thread_info(tsk));
132#endif
133}
134
135/*
136 * Flush thread state. This is called when a thread does an execve()
137 * Note that we flush coprocessor registers for the case execve fails.
138 */
139void flush_thread(void)
140{
141#if XTENSA_HAVE_COPROCESSORS
142 struct thread_info *ti = current_thread_info();
143 coprocessor_flush_all(ti);
144 coprocessor_release_all(ti);
145#endif
146 flush_ptrace_hw_breakpoint(current);
147}
148
149/*
150 * this gets called so that we can store coprocessor state into memory and
151 * copy the current task into the new thread.
152 */
153int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
154{
155#if XTENSA_HAVE_COPROCESSORS
156 coprocessor_flush_all(task_thread_info(src));
157#endif
158 *dst = *src;
159 return 0;
160}
161
162/*
163 * Copy thread.
164 *
165 * There are two modes in which this function is called:
166 * 1) Userspace thread creation,
167 * regs != NULL, usp_thread_fn is userspace stack pointer.
168 * It is expected to copy parent regs (in case CLONE_VM is not set
169 * in the clone_flags) and set up passed usp in the childregs.
170 * 2) Kernel thread creation,
171 * regs == NULL, usp_thread_fn is the function to run in the new thread
172 * and thread_fn_arg is its parameter.
173 * childregs are not used for the kernel threads.
174 *
175 * The stack layout for the new thread looks like this:
176 *
177 * +------------------------+
178 * | childregs |
179 * +------------------------+ <- thread.sp = sp in dummy-frame
180 * | dummy-frame | (saved in dummy-frame spill-area)
181 * +------------------------+
182 *
183 * We create a dummy frame to return to either ret_from_fork or
184 * ret_from_kernel_thread:
185 * a0 points to ret_from_fork/ret_from_kernel_thread (simulating a call4)
186 * sp points to itself (thread.sp)
187 * a2, a3 are unused for userspace threads,
188 * a2 points to thread_fn, a3 holds thread_fn arg for kernel threads.
189 *
190 * Note: This is a pristine frame, so we don't need any spill region on top of
191 * childregs.
192 *
193 * The fun part: if we're keeping the same VM (i.e. cloning a thread,
194 * not an entire process), we're normally given a new usp, and we CANNOT share
195 * any live address register windows. If we just copy those live frames over,
196 * the two threads (parent and child) will overflow the same frames onto the
197 * parent stack at different times, likely corrupting the parent stack (esp.
198 * if the parent returns from functions that called clone() and calls new
199 * ones, before the child overflows its now old copies of its parent windows).
200 * One solution is to spill windows to the parent stack, but that's fairly
201 * involved. Much simpler to just not copy those live frames across.
202 */
203
204int copy_thread(unsigned long clone_flags, unsigned long usp_thread_fn,
205 unsigned long thread_fn_arg, struct task_struct *p,
206 unsigned long tls)
207{
208 struct pt_regs *childregs = task_pt_regs(p);
209
210#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
211 struct thread_info *ti;
212#endif
213
214 /* Create a call4 dummy-frame: a0 = 0, a1 = childregs. */
215 SPILL_SLOT(childregs, 1) = (unsigned long)childregs;
216 SPILL_SLOT(childregs, 0) = 0;
217
218 p->thread.sp = (unsigned long)childregs;
219
220 if (!(p->flags & PF_KTHREAD)) {
221 struct pt_regs *regs = current_pt_regs();
222 unsigned long usp = usp_thread_fn ?
223 usp_thread_fn : regs->areg[1];
224
225 p->thread.ra = MAKE_RA_FOR_CALL(
226 (unsigned long)ret_from_fork, 0x1);
227
228 /* This does not copy all the regs.
229 * In a bout of brilliance or madness,
230 * ARs beyond a0-a15 exist past the end of the struct.
231 */
232 *childregs = *regs;
233 childregs->areg[1] = usp;
234 childregs->areg[2] = 0;
235
236 /* When sharing memory with the parent thread, the child
237 usually starts on a pristine stack, so we have to reset
238 windowbase, windowstart and wmask.
239 (Note that such a new thread is required to always create
240 an initial call4 frame)
241 The exception is vfork, where the new thread continues to
242 run on the parent's stack until it calls execve. This could
243 be a call8 or call12, which requires a legal stack frame
244 of the previous caller for the overflow handlers to work.
245 (Note that it's always legal to overflow live registers).
246 In this case, ensure to spill at least the stack pointer
247 of that frame. */
248
249 if (clone_flags & CLONE_VM) {
250 /* check that caller window is live and same stack */
251 int len = childregs->wmask & ~0xf;
252 if (regs->areg[1] == usp && len != 0) {
253 int callinc = (regs->areg[0] >> 30) & 3;
254 int caller_ars = XCHAL_NUM_AREGS - callinc * 4;
255 put_user(regs->areg[caller_ars+1],
256 (unsigned __user*)(usp - 12));
257 }
258 childregs->wmask = 1;
259 childregs->windowstart = 1;
260 childregs->windowbase = 0;
261 } else {
262 int len = childregs->wmask & ~0xf;
263 memcpy(&childregs->areg[XCHAL_NUM_AREGS - len/4],
264 ®s->areg[XCHAL_NUM_AREGS - len/4], len);
265 }
266
267 childregs->syscall = regs->syscall;
268
269 if (clone_flags & CLONE_SETTLS)
270 childregs->threadptr = tls;
271 } else {
272 p->thread.ra = MAKE_RA_FOR_CALL(
273 (unsigned long)ret_from_kernel_thread, 1);
274
275 /* pass parameters to ret_from_kernel_thread:
276 * a2 = thread_fn, a3 = thread_fn arg
277 */
278 SPILL_SLOT(childregs, 3) = thread_fn_arg;
279 SPILL_SLOT(childregs, 2) = usp_thread_fn;
280
281 /* Childregs are only used when we're going to userspace
282 * in which case start_thread will set them up.
283 */
284 }
285
286#if (XTENSA_HAVE_COPROCESSORS || XTENSA_HAVE_IO_PORTS)
287 ti = task_thread_info(p);
288 ti->cpenable = 0;
289#endif
290
291 clear_ptrace_hw_breakpoint(p);
292
293 return 0;
294}
295
296
297/*
298 * These bracket the sleeping functions..
299 */
300
301unsigned long get_wchan(struct task_struct *p)
302{
303 unsigned long sp, pc;
304 unsigned long stack_page = (unsigned long) task_stack_page(p);
305 int count = 0;
306
307 if (!p || p == current || p->state == TASK_RUNNING)
308 return 0;
309
310 sp = p->thread.sp;
311 pc = MAKE_PC_FROM_RA(p->thread.ra, p->thread.sp);
312
313 do {
314 if (sp < stack_page + sizeof(struct task_struct) ||
315 sp >= (stack_page + THREAD_SIZE) ||
316 pc == 0)
317 return 0;
318 if (!in_sched_functions(pc))
319 return pc;
320
321 /* Stack layout: sp-4: ra, sp-3: sp' */
322
323 pc = MAKE_PC_FROM_RA(SPILL_SLOT(sp, 0), sp);
324 sp = SPILL_SLOT(sp, 1);
325 } while (count++ < 16);
326 return 0;
327}